The D-Tuna would work if the following conditions are met on your guitar:
1. The floating tremolo in question is an Original Floyd Rose or variant of it. This means that the tremolo would need to have the traditional allen screws that screw into the saddle piece that keeps the saddle blocks (and the string) in place. Lo-Pro and other styles will simply not work.
2. The tremolo routing in your guitar is NOT recessed. Basically, the tremolo itself would have to sit on the body itself. If there is an extra cavity cut out that allows you to pull up on the tremolo, it will just knock the rest of the string out of tune when you use the D-Tuna.
The D-Tuna is for all intensive purposes a really quick method of changing the position of the fine tuner on your string. To get an idea on how this works, first play around with your fine tuner and watch the tuning screw push down on the allen screw from the butt end of your guitar. Now put your fine tuner back in its original position and push down on the allen screw yourself. That is exactly what the D-Tuna does; releases and adds string tension to one string as needed depending on its location. The rule of physics concerning tremolos (especially floating ones) goes like this: if string tension on one string changes, it changes the tension of all the other strings in the opposite manner that was originally performed (for every action there is an equal and opposite reaction). When a string is tuned down from say B to A, it will cause the bridge to drop down into the body, thus making the other strings raise up in pitch. The only real way to counteract this is to have the tremolo sitting against the body so that it cannot move when string pitch (tension) is decreased.
I have one of two suggestions for you:
1. Use multiple guitars
2. Invest in fixed bridge guitars (see also: suggestion 1
)
Again, unless both conditions above are met, there is no "quick fix" for changing tunings on a floating bridge. At the very least a new setup is required to change from a B to A tuning. An entirely new set of strings are also required (along with a whole new setup to accomodate them) for E standard. Let's face it - a set of 12's or 13's in E standard tuning with a floating bridge is downright impossible.
That is just way too much string tension for the bridge to work with (even with all five springs installed).